中文摘要：

用天然气掺加氮气来模拟煤层气燃料,在一台由柴油机改装的单缸火花点火发动机上开展了燃用煤层气时的燃烧特性,包括燃烧期及其循环变动性能的试验研究,结果表明,不同负荷下,随着氮气体积分数的增加,最大缸压对应的曲轴转角延迟,压力升高率降低,火焰发展期明显变长。当氮气体积分数为20%时,燃烧较稳定,当氮气体积分数增大至30%时,燃烧循环变动明显加剧,但随着发动机负荷的增加循环变动减小。

英文摘要：

By using natural gas blended with nitrogen to simulate coal-bed gas fuel,an experimental study is carried out on the combustion characteristics,including the duration of different combustion phases and the behavior of cycle variation of a single cylinder spark ignition engine,refitted from a diesel engine and fuelled with coal-bed gas.The results show that with the increase in nitrogen volume fraction,the moment corresponding to maximum cylinder pressure delays,pressure rising rate decreases and the duration of flame development phase increases markedly.When nitrogen volume fraction is 20%,combustion is stable.But with nitrogen volume fraction rising to 30%,the cycle to cycle variation increases obviously but the variation lowers in high load operations.